A long-simmering debate over plans for Honolulu's mass transit system is expected to heat up again Thursday when a City Council panel considers what type of vehicles it should feature.

At stake are lucrative vehicle supply contracts worth hundreds of millions of dollars and the character of a transit system that could shape O'ahu's future for decades.

A final decision is months away, and the council remains undecided about whether a group of nationally recognized transportation experts should make the call, as Mayor Mufi Hannemann has proposed.

A vote on whether to create the expert group could come later this month, but it remains unclear whether the experts would be advisory or decision-making. Some council members are adamant that the council should make the vehicle selection.

The council's Transportation Committee on Thursday will consider a bill that could specify whether the transit system should feature steel tracks and rails or another option, such as a monorail on rubber tires or a train that glides on a cushion of magnetic levitation.

Council Transportation Chairman Nestor Garcia said his main goal Thursday is to ensure the process is transparent.

"There appears to be some concern that this is all closed-door, and that decisions have allegedly been made already," he said. "This will be a chance for the public to weigh in and see what they would like (the group of experts) to consider."

The council panel could advance an incomplete bill Thursday as a placeholder, without specifying the vehicle technology.

That would move the process forward and help minimize delays as the debate continues.

A firm decision on the type of vehicle must be made before an environmental impact statement for the project can be completed and allow construction to begin. Hannemann hopes to break ground by 2009.

The 34-mile system is expected to cost $5 billion and run from Kapolei to Ala Moana, with spurs to Waikiki and Manoa.